Best way to clean old aluminum for TIG
I have some old (1/4") diamond plate aluminum that has lots of pitting and needs clean-up in order to make a foot pedal housing for a foot pedal project for the TIG.
I don't think wire wheel would clean the pits. Is there a mild acid bath that would work?
Phosphoric acid works great!
I have tried many things, including a trip to the local hydroponic growing store (Gee, wonder what people go there for?:P). They sell a product called "pH down" which is basically food-grade phosphoric acid in a decent concentration. They have really diluted it in recent years, as back in the day when I was an actual customer of this place (YEARS ago), the directions called for like 20% of the recommended application that the newer formula does. But, I bought a pint, just to see. I applied it with a clean cloth, and it INSTANTLY brightened the surface to a shiny finish. On deeper oxidation, a little help from a red scotchbrite pad helped, but the key was to keep the solution moving, not just wet it and let it sit. Then rinse thoroughly and immediately. You're doing yourself no favors by letting the stuff dry on the part. Another product that I've had great results with is Kleen-Strip's "Concrete Prep n Etch". It's a phosphoric acid-based etchant for getting old concrete ready for over-coating. The product cost was to the best of my recollection, less than ten bucks for a 3-quart jug. It gave good results FOR ME, and before any further action was taken, I RINSED thoroughly with plain, hot water. You want to get ALL remaining product off the base metal, as it will keep on working as long as it's on the metal.
I must put a disclaimer here: Neither of the products mentioned above is labelled as an aluminum cleaner, my experiences may be different from yours, the whole of my intent is to relay my personal experience using different products for different applications. Should you decide to experiment with the above mentioned products in any way not specified on the label, you do so at your own risk, and without any endorsement by me whatsoever. See, that wasn't so bad, now was it;)